Charles e



(No Model.)

0. E. SGRIBNER.

APPARATUS FOR TELEPHONE SWITGHBOARDS. No. 512,399.

Patented Jan. 9, 1894.

INVENTEIR WITNESSES RAFMING COMPANY UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, OF SAME PLACE.

APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 512,399, dated January9, 1894.

Application filed April 26, 1893- Serial No. 471,979. (No model.) I

To all whom it may concern.-

Be it known that 1, CHARLES E. SCRIBNER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Apparatus forTelephone- Switchboards, (Case N o. 330,) of which the following is afull, clear, concise, and exact description, reference being had to theaccompanying drawings, forming a part of this specification.

My invention relates to apparatus for restoring or resetting signalreceiving annunciators of telephone switchboards its primary object isto provide means for resetting the annunciators electrically by amomentary current controlled by a key actuated in the performance ofsome act involved in the establishment of connection between lines.

Hitherto in telephone exchange systems it has been common to employ selfrestoring annunciators comprising two electro-magnets, one of which,designated the operating coil, acts to display or actuate the indicator,while the other, the restoring coil, operates to replace the indicatorto its normal position, the operating coil being ordinarily connected inthe line circuit and the restoring coil being included in a localbattery circuit adapted to be closed by the act of establishingconnection with the line, and remaining closed during the continuance ofthe connection. In connection with the plug circuit by means of whichlines are united for communication, a clearing-out annunciator is placedfor receiving the signal for disconnection, the restoring magnet of theclearing-out annunciator being also in a local circuit adapted to beclosed by the operator in the manipulation of the switching appliances.I

In my invention I connect the operating coils of the differentannunciators with the signaling circuit of the telephone line, andarrange the restoring coils of the annunciators in local circuitsadapted to be closed 'incidentally in the operation of the ringing keyby which the operator .sends a call signal to a substation after thecompletion of a connection therewith. The local restoring circuit may,if desired, be a portion of the signaling circuit thus closed by theoperator in calling,

in which casev the signaling generator serves as the source of currentfor resetting the different annunciators.

'A further object of my invention is to preserve permanently thecontinuity of the conductors of the plug circuit, avoiding the inclusionof contact points in the circuit to disconnect the clearing-outannunciator while a call signal is being sent in order to prevent itsoperation thereby. This object is attained by the construction which Ihave described, applied to the clearing-out annuncia tor, which in myinvention is retained inoperative by the signaling currentwhich is beingtransmitted to the substation.

My invention will be more fully understood by reference to theaccompanying drawings, which is illustrative thereof.

In the drawings I have shown two telephone substations .connected bylines with the usual springjacks and with annunciators upon a telephoneswitchboard, switching appliances being shown upon the switchboard inposition of connecting the two lines together, the various circuitsbeing arranged in accordance with my invention.

In the drawings, the substations l and 2 are represented as equippedwith the usual apparatus, comprising a telephone transmitter a, areceiver a, a generator a of signaling current, and a bell 0. adapted torespond to such currents, the telephonic and the signaling appliancesbeing connected, respectively, with the contact points of a switch 0.adapted to connect the telephone set or signaling instruments intocircuit as the telephone is removed from or replaced upon the switchhook. The generator 01, is provided with an automatic switch of wellknown construction, adapted to open the connection of the .frame of thegenerator to one side of the line, when the generator is operated, andto close the circuit of the grounded armature to the frame instead. Theapparatus of station 1 is connected by 5 line wires 19 and b with thedifferent contact pieces, respectively, of springjacks c and c, whichare assumed to be located upon a multiple switchboard at a centraloffice, the different springjacks c and 0' being placedupon toodifferent sections (1 and cl of the multiple board. At one of the boardsdf is a self-restoring signaling annunciator e, whose operating coilf isconnected in a branch from one side I) of the line to earth, and whoserestoring coil f is connected in another branch from the side I) of theline to earth. The apparatus of substation 2 is similarly connected bylines I) and b with like apparatus upon the switchboard, the springjacksc and c of the line being arranged upon the sections at and d of theswitchboard, but the annunciator 2' being placed upon the section d ofthe switchboard in order to be under the attendance of another operator.

The switching apparatus is shown complete at section (Z of theswitchboard. This apparatus comprises a pair of loop connecting plugs gand 9 whose like contact pieces are connectedthroughconductorshand h.hen the two plugs are inserted into two springjacks of different lines,the limbs of the line circuits are thus continued through the contactpieces of their respective springjacks to the co-operating contacts ofthe loops plugs and to the conductors It h of the plug circuit. Thus thetwo lines are united into a continuous electric circuit. The operatingcoil f of a self-restoring clearing-out annunciator t is connected in apermanent bridge connection between the different conductors h and h. Acalling key it is arranged with contact springs connected with theconductors 7t 7t of the plug circuit, the branch from one of the springsincluding the restoring coilf' of the annunciator i. The correspondingcontact anvils of the key are connected with the poles of a generator Zof signaling current. An operators telephone set on is furnished for theoperator, connected with a key a, by which the telephone may be broughtinto connection with the plug circuit h h. A battery 0 is shownconnected with the conductor h of the plug circuit, for testingpurposes, a retardation coil being included between the battery and theplug circuit to prevent the shunting of telephonic current to earth.

I will now trace the operations involved in establishing such connectionbetween the stations 1 and 2. The subscriber at station 1, who initiatedthe connection, by rotating his signal generator a transmits a signalingcurrent over thelinebto the central ofiice, where it finds circuitthrough the operating coil f of the annunciatore. The switch upon thegenerator a opens the normally closed branch connection between thesides I) and b of the line at the substation so that no current passesthrough'the line b. The operating coilf is energized, and, the restoringcoil f being unmagnetized, the annunciator is operated and indicates thesignal to the attendant at switchboard d. The operator at once inserts aplug g into the springjack c and depresses the plunger of her listeningkey at. Her telephone set is thus looped into a connection with theapparatus at the substation, and when the subscriber has removed histelephone from the switch hook he may give an oral order forthe'connection desired to the operator the centralstation.Theoperatorhavingrecelved the order tests theline called for to determne whether it is in use or not at the other section d of theswitchboard. This she does by applying to the thimble or ring of thespring ack c of line to station 2, the tip of thtla remainin lu as thetip of a p ug1s siown appli ec l re uilt; test ring c upon switchboard(Z. If the line thus tested be in use a grounded battery 0 is connectedwith the test rings through the medium of the plug circuit by which suchconnection already ex1sts, and all the rings of the springjacks ofthatlme are electrified to a difference of potential from the earth.When, under this condition, the tip of plug g is applied to the ring acircuit from a test ring to earth is created through the conductor h ofthe plug circuit and aportion of the coil of the operators telephonereceiver m, and the current set up in thiscrrcuit causes a click orother characteristic sound in the telephone, which signifies thecondition of the line to the operator making the test. Finding the lineto station 2 not in use, the operator inserts the plug g fully into thespringjack 0 thus completing the connection between the two substations,after which she disconnects her telephone from the circuit. Finally shedepresses the plunger of the ringingkey 7t, looping the generator lintocircuit with the conductors h h of the plug circuit. The current fromthe generator to the conductor h traverses the restoring co 1l f of theclearing-out annunciator 1; this clearing-out annunciator may be assumedto be in position to display its indicatoryhaving remained in thatposition since the d1sc onnection signal of the last connection in whichthe plug circuit was employed. The magnetf 15 now energized by thecurrent traversing 1t and acts to restore the indicator of theannunciator, placing the annunciator in COlldl'ElOlhtO respond tosignaling current. Several circuits exist for the current of thegenerator Z from the plug circuit h h. the operating coil of theclearing-out annunciator 1:; but the annunciator is not aifected by thiscurrent since the restoring (3011f: is at the same moment exercising itsfunction of resetting the indicator. Another path 1s through the plugcircuit to the plug 9', thence over the lines b and b to substation 2and through the signaling bell a? at that statlon. The signaling bell isthus operated and calls the attention of the subscriber at station 2 tothe existence of connection with his line. A portion of the current isshunted from the lines I) b through the two maguetsfand f of theindividual annunciator e of that line; but since both magnets of theannunciator are thus simultaneously energized the indicator of theannunciator is not operated and no signal is given. Another portion ofthe signaling current finds circuit to the plug g and thence to theconductors b b extending to station 1. The current divides also at theseOne of these is through conductors, a portion passing through each ofthe coils f and f of the annunciator e, and another portion passingthrough theline circuit to the station and through the bell or telephonethereat. The current finding circuit through the restoring magnet ofannunciator e energizes that magnet and resets the displaced indicatorof the annunciator. The current through the telephone or hell at thesubstation 1 indicates to the subscriber that the connection has beencompleted.

When the subscribers at the difierent substations have completed theirconversation,

either one may send a signal for disconnection.

Assuming that subscriber at station 1 does this, the current from hissignaling generator 0, finds circuit over line b to the springjack c atwhich the connection is made, from which point it has two paths. One ofthese is directly through the operating coil f of individual annunciatore to earth; the other is through the line spring of the jack to the tipof the plug g and thence to the conductor h; from this conductor thecurrent finds sevther portion of the current escapes through bothconductors h and h to the line conductors 19 11 of line to station 2 andfrom these lines through the two magnets of the individual annunciator eand through the bell at substation 2; but the individual annunciator ofthisline is also not operated since both its magnets are energized. Thusneither of the individual annunciators displays its indicator, While theclearing-out annunciator is operated and signifies to the attendant thatthe connection between the lines is no longer desired. When the plugs gg have been removed from the springjacks, the circuits are restored tothe condition in which their annunciators are free to respond to callsignals from their respective stations.

Having thus described my invention, 1 claim as new and desire to secureby Letters Patent- 1. The combination with the two limbs of a telephoneline extending from a substation to a central otfice, of a signal bellbridged between the limbs at a substation, a self-restoring annunciatorat the central office having its two magnets in series in abridgebetween the two limbs, and a source of signaling current connected in abridge between the two limbs, whereby the signaling bell is operatedwhile the annunciator is reset and prevented from displaying itsindicator, substantially as described.

2. The combination with springjacks upon a multiple switchboard eachcomprising two insulated contacts, of conductors connecting the likecontact points of the different springjacks together, a self-restoringannunciator having one of its magnets connected with each of saidconductors, a connecting plug insert ed into the springjack having onecontact piece making connection with the restoring coil of theannunciator, a manually operated k'ey adapted to connect a source ofelectric current with said contact piece of the plug, whereby theannunciator may be reset by momentarily operating the key whileconnection exists with the line, substantially as described.

3. The combination with a connecting plug, of theoperating magnet of anannunciator connected therewith, said annunciator being provided with aretaining or restoring electromagnet adapted, when energized, to preventthe actuation of the indicator of the annunciator, a generator ofsignal'current, a key for connecting the source of signaling currentwith the connecting plug, and means for energizing the retaining orrestoring magnet of the annunciator simultaneously with the sending ofsignaling current to prevent the operation of the clearing-outannunciator thereby, substantially as described.

4. The combination with two connecting plugs, of continuous conductorsconnecting the like parts of the two plugs together, a selfrestoringannunciator having its operating coil connected with the plug circuit, agenerator of signaling current, a key for connecting the same with theplug circuit, the restoring or retaining coil ofthe self-restoringannunciator being included in the normallyopen circuit of the generator,substantially as described.

In witness whereof I hereunto subscribe my name this 22d day of March,A. D. 1893.

CHARLES E. SCRIBNER. Witnesses:

ELLA EDLER,

LUCILE RUSSELL.

